Strategies To Discover the Structural Components of Cyst and Oocyst Walls
Open Access
- 1 December 2013
- journal article
- review article
- Published by American Society for Microbiology in Eukaryotic Cell
- Vol. 12 (12), 1578-1587
- https://doi.org/10.1128/ec.00213-13
Abstract
Cysts of Giardia lamblia and Entamoeba histolytica and oocysts of Toxoplasma gondii and Cryptosporidium parvum are the infectious and sometimes diagnostic forms of these parasites. To discover the structural components of cyst and oocyst walls, we have developed strategies based upon a few simple assumptions. Briefly, the most abundant wall proteins are identified by monoclonal antibodies or mass spectrometry. Structural components include a sugar polysaccharide (chitin for Entamoeba , β-1,3-linked glucose for Toxoplasma , and β-1,3-linked GalNAc for Giardia ) and/or acid-fast lipids ( Toxoplasma and Cryptosporidium ). Because Entamoeba cysts and Toxoplasma oocysts are difficult to obtain, studies of walls of nonhuman pathogens ( E. invadens and Eimeria , respectively) accelerate discovery. Biochemical methods to dissect fungal walls work well for cyst and oocyst walls, although the results are often unexpected. For example, echinocandins, which inhibit glucan synthases and kill fungi, arrest the development of oocyst walls and block their release into the intestinal lumen. Candida walls are coated with mannans, while Entamoeba cysts are coated in a dextran-like glucose polymer. Models for cyst and oocyst walls derive from their structural components and organization within the wall. Cyst walls are composed of chitin fibrils and lectins that bind chitin ( Entamoeba ) or fibrils of the β-1,3-GalNAc polymer and lectins that bind the polymer ( Giardia ). Oocyst walls of Toxoplasma have two distinct layers that resemble those of fungi (β-1,3-glucan in the inner layer) or mycobacteria (acid-fast lipids in the outer layer). Oocyst walls of Cryptosporidium have a rigid bilayer of acid-fast lipids and inner layer of oocyst wall proteins.Keywords
This publication has 83 references indexed in Scilit:
- Tissue destruction and invasion by Entamoeba histolyticaTrends in Parasitology, 2011
- A simple fibril and lectin model for cyst walls of Entamoeba and perhaps GiardiaTrends in Parasitology, 2011
- Molecular characterisation of a novel family of cysteine-rich proteins of Toxoplasma gondii and ultrastructural evidence of oocyst wall localisationInternational Journal for Parasitology, 2010
- Isolation of Toxoplasma gondii development mutants identifies a potential proteophosphogylcan that enhances cyst wall formationMolecular and Biochemical Parasitology, 2010
- EuPathDB: a portal to eukaryotic pathogen databasesNucleic Acids Research, 2009
- Development of forward genetics in Toxoplasma gondiiInternational Journal for Parasitology, 2009
- Toxoplasma gondii: 25 years and 25 major advances for the fieldInternational Journal for Parasitology, 2009
- Unique Asn-linked Oligosaccharides of the Human Pathogen Entamoeba histolyticaOnline Journal of Public Health Informatics, 2008
- A hundred-year retrospective on cryptosporidiosisTrends in Parasitology, 2008
- Encystation of Giardia lamblia: a model for other parasitesCurrent Opinion in Microbiology, 2007